The proof of the pudding is in the eating, as an old English proverb says. In other words: even the best design concepts are just as good as they turn out to be in practice, confronted with real users in the day-to-day operation of buildings. This realization is key to the projects on the following pages. All of them were designed to achieve optimal indoor comfort, and their performance has undergone a thorough reality check after completion. The results provide valuable insight into the hidden links between building design and operation and human health and well-being.

By Jakob Schoof

A formal post-occupancy evaluation is not being carried out at Green Solution House but according to hotel director Trine Richter, conference guests regularly report that, thanks to the pleasant indoor climate and plenty of daylight, they feel fresh even after a long day with numerous slideshows. “This means that the return on investment on a conference is a lot higher here,” says Richter.

Design approach
The former Hotel Ryttergården from 1973 has been renovated and supplemented with a daylit congress centre that directly adjoins the newly landscaped grounds at the back of the building. Three sustainability concepts inspired the building design: the DGNB system, the cradle-to-cradle principle aimed at a circular flow economy, and the Active House specifications, with a focus on healthy indoor climate and daylight supply.
While the new foyer has a modular glass roof with integrated PV cells, sun tunnels and flat roof windows also bring light deep into the building elsewhere. Daylight factors of 6.6% in the conference centre and 3.0% in some of the hotel rooms are achieved. In order to ensure a good indoor air quality, the building is fitted with various new kinds of air-cleaning products such as dust-absorbing carpets, wall panels that neutralise formaldehyde, and a ‘green’ wall that cleans the air. Two of the hotel rooms were fitted out as ‘smart rooms’ in which a custom-designed app tracks the impact of the guest’s stay, monitoring water and energy consumption, daylight levels and air quality, as well as temperature and humidity levels.

Results
In the Active House evaluation, the Green Solution House scored the highest level in terms of thermal environment, indoor air quality and sustainable construction, and level 2 out of 4 in terms of daylight.
Since September 2017, the foyer and conference spaces have also been equipped with sensors for a live monitoring of comfort parameters such as CO2, temperature and humidity. Results are available in real time at gsh.leapcraft.dk. For an easily comprehensible evaluation of the indoor climate, Leapcraft has developed the Comfort Economy Wheel. This graphic displays the measurements of eight parameters (from daylight levels to VOCs) from the past seven days, and compares them to the calculated results from the design phase on a scale derived from the Active House specification. The centre of the wheel indicates an overall evaluation of how well the building is doing, from Poor (Level 4) to Good (Level 1)
During the first four months of the monitoring, CO2 levels in the conference area were almost always less than 500 ppm above outdoor levels. Only in some instances with higher occupancy were levels closer to 1,000 ppm reached. Indoor temperatures remained within the 22–26°C bracket during the entire period.
In the foyer, the measured air quality was even better, which may be due to the natural influx of fresh air through the opening and closing entrance doors. Temperature fluctuations tended to be larger in this area, though, with indoor temperatures dropping below 18 °C occasionally in winter.

“I like the Active House approach to sustainability. Compared to other certification schemes, Active House emphasises comfort much more coherently. This made it easier to think about how people were actually going to experience the building.”

Trine Richter, hotel director

Derwenthorpe was designed in such a way as to foster social cohesion between different types of tenure, with a mix of private homes and houses for social rent. According to the post-occupancy evaluation report, this strategy had mixed success.
“Early interviewees were generally positive, but later ones pointed to an emerging sense of difference between tenure types. There were disproportionately more contacts among home owners than between owners and social renters, although links existed across all tenures.”

Design approach
Due for completion in 2018, Derwenthorpe is a mixed-tenure sustainable community of 540 energy-efficient homes on the eastern periphery of York. The two- to four-bedroom (90 m2 to 120 m2) homes have flexible rooms, designed in accordance with the Lifetime Homes Standard. Dual-aspect main living rooms and 2.60- to 2.70 m-high ceilings bring natural light deep into the houses and allow cross ventilation throughout the year. The larger facade windows generally face south and many houses have sunspaces to maximise useful solar gain. These act as a thermal buffer throughout the year, collecting solar energy in the winter and helping to cool the houses in summer, and make use of the stack effect for ventilation.

Results
The first phase of Derwenthorpe (built 2012–2013) has been thoroughly evaluated, both in terms of energy performance and user satisfaction. It turned out that the design of the homes, particularly daylight and space standards, as well as the location were the main factors that drew new residents to the community. Derwenthorpe’s green credentials were usually only a subsidiary factor or added bonus.
Nine out of ten residents were satisfied with their homes. The post-occupancy evaluation also revealed that residents’ level of connectedness within the community was very high. As a result of the energy efficiency standard of the homes, residents had lower than average carbon foot prints from energy use in their homes compared with national survey respondents. However, it turned out that residents often did not know how to operate the energy-efficiency measures such as the sunspaces, MVHR systems or the communal heating systems properly. It was also difficult to change travel patterns, despite efforts to support more sustainable options e. g. with bicycle vouchers, an electric bus to the city centre and an on-site car club. Few households had substantially reduced their car use after moving to Derwenthorpe.

“This is a truly sustainable approach from inception to completion, and can only be described as exemplary and what all housing developments should aspire to”

According to Russell Ibbotson, living in Active House Centennial Park enabled him to connect physical measurements and subjective well-being for the first time. “It wasn’t until I was able to measure the quality of the air in the house and correlate this with how I felt that I realised how much I was personally affected by indoor air quality. I now appreciate how poor air quality makes me unfocused and even drowsy. I also noticed that I wake more frequently when the air quality is poor ...”

Design approach
This private home in the suburban West End of Toronto is the world’s first certified Active House. Its C-shaped floor plan is arranged around a central courtyard that brings daylight into the central stair and core area. When the windows are open, the home’s overall design supports cross- and stack ventilation, thereby minimising the need for air conditioning. The ground floor living room, dining area and kitchen are laid out in an open plan, with no barriers to obstruct daylight other than a see-through fireplace system dividing the dining and living areas. Double-height spaces (e. g. in the living room) vertically connect the two levels of the house. Ten roof windows and four sun tunnels bring natural light even into the secondary rooms of the upper floor.

Evaluation concept
After completion of the building, Russell Ibbotson, Technical Manager at VELUX Canada, moved into the house together with his family for half a year and reported his personal experience in a blog. Alongside this, a third-party research group equipped the house with sensors to take quantitative measurements of daylight, energy and the indoor climate.

Results
In the Active House evaluation, the house scores particularly high on indoor air quality, the thermal environment, energy supply and freshwater consumption. The average daylight factor has been calculated at 3.4 % using the VELUX Daylight Visualizer software. In the living room and in the upstairs bedrooms, daylight factors above 4% are achieved.
During the half-year stay of the test family in late 2016, Active House Centennial Park provided excellent thermal comfort, particularly in the cold season. With one minor exception, the house also performed amazingly well in summer, as Russell Ibbotson reports − “Most of the house was very comfortable, even on those super-hot 30°C+ days that Toronto had so many of this year. The only space of concern was the family room on hot sunny afternoons.” According to Ibbotson, external blinds in front of the southwest facing window could have solved this issue „but most North Americans wouldn’t accept the aesthetic“.
Indoor air quality also proved to be good throughout the monitoring period. Only in a bedroom with two children sleeping in it did CO2 levels regularly climb over 1,000 ppm. The spells of intense heat in summer also proved to be a challenge. The energy recovery ventilation tended to drive humidity levels in the house up, and the air conditioning lead to high CO2 levels after a day of uninterrupted operation without any ventilation. “In the end, it was easier to manage the air quality and humidity by opening the windows for 10–15 minutes on the hot and humid days for a good old European airing,” writes Russell Ibbotson in his blog.

The value of a building depends on the quality of the technology and the solutions that are used to manage the building. Light, ventilation, safety etc. must play together in accordance with the purpose of the building – whether it is used for learning, development, treatment or growth. Data plays a vital role in that interplay. And there’s no doubt in my mind that it will come to play an even bigger role.”

Jesper Skov, CEO, Siemens Building Technologies

Design approach
The new Siemens Denmark headquarters replaces the former office building of the technology company, located on the same site in a suburban industrial area west of Copenhagen. 900 employees work inside the abstract, five-storey cube, which is clad with white and dark grey concrete panels on the outside. Inside the building, the reception, canteen, showrooms and seminar rooms are located on the ground floor, while offices occupy the majority of the upper floors. A central, full-height atrium supplies the interior with daylight through six glazed ridgelights, each measuring 17 metres in length, which comprise a total of 228 fixed modular skylights. Shading in the central space is provided by awnings that are automatically controlled by sensors depending on seven different parameters, including the position of the sun and the lux levels in the atrium.

Evaluation concept
The Siemens headquarters was one of the first buildings in Denmark to achieve LEED Gold certification. The building has been equipped with temperature-, CO2 -, electricity- and other sensors from the beginning. This allows the facility management team to monitor the energy consumption in the building, as well as the indoor comfort in any room they choose to, in order to be able to adjust the systems accordingly.

Results
So far, the selective monitoring has allowed the technicians to understand the thermal behaviour of different spaces much better and to fine-tune the cooling and ventilation systems. The diagrams below are an example: they show the CO2 levels and indoor temperature in a meeting room for 30 days in March 2018. Both curves rise rapidly once the room is occupied, but only to the point where the ventilation system (which is controlled by sensors) automatically reacts by increasing the volume, as well as lowering the temperature, of the incoming fresh air.

The LEED certification also includes an evaluation of the volume of daylight in the building, which can be difficult to predict at the planning stage. To help document the effect, the VELUX Group has developed a number of building simulation tools, which can be used to simulate the impact of the modular skylights.

Temperature and CO2 measurements
in a conference room in March 2018

With a timber frame construction, wood wool ceilings and carpet tiles made of recycled rubber tires, Architype also sought to minimise the embodied carbon content of the building. The Corten steel cladding is a nod to the industrial heritage of the site.

Design approach
This primary school for 430 pupils, which also includes a 30-place nursery, is located on a former ironworks site that dates back to the time of the Industrial Revolution. The new building replaces a former school that had been badly damaged in an arson attack. Its section rises to the south, providing two floors of classrooms with south-facing windows. Clerestory windows on both sides provide natural light to the double-height hub space in the building centre. The south facade features extensive roof overhangs and projecting canopies that shade the windows from the summer sun but reflect low sun deep into the building in winter. The ventilation is based on a centralised MVHR system that operates throughout the year to assure a supply of fresh air to the occupied spaces at all times. In summer mode, the heat exchanger of the MVHR system is bypassed. Additionally, the classrooms have a number of low level windows that enable the occupants to experience air flow from the outside. In summer nights, ventilation flaps in the facades and high level vents in the central hub space can be opened to help cool down the building for the next day.

Results
Building monitoring was undertaken by Architype in collaboration with Coventry University, and the building was fine-tuned in a Soft Landings process that also involved post-occupancy evaluation. The temperatures in the classrooms turned out to be very stable. During a typical week in summer, peak temperatures in a test classroom remained around 3°C lower than in a conventional school from the 1970s, and around 2°C lower than those in previous schools designed by Architype. The architects attribute this to a slight reduction and more balanced distribution of glazing in the facades, and to the night time purge ventilation in the new school.
Air quality also turned out to be much better than in the previous schools, where the architects had still relied entirely on manual ventilation in summer − but experience showed that the teachers were not opening the windows frequently enough. With the continuous mechanical ventilation in place, CO2 levels in the test classroom remained below 1,000 ppm most of the time during a typical winter week, and well below the 1,000 ppm threshold in summer.
The measured energy consumption matched the design stage predictions much more closely than in average buildings. Primary energy use in the first year was at 143 kWh/m2a, compared to a calculated figure of
120 kWh/m2a.

The building draws an unusual heat source for its heating: The in-house heat pump is connected to a nearby urban sewer in which a 55-metre long heat exchanger has been installed. The sewage water has a temperature between 15 and 20°C all year round. In this way, the Aktiv-Stadthaus uses an efficient energy resource that is still completely ignored in most cities around the world.

Design approach
This new build with 74 apartments is the first multi-storey apartment building in Germany to meet the Efficiency House Plus standard. Over the course of the year, it is expected to generate more energy on its own property than its residents consume. The shape of the building results from the dimensions of the property: 150 metres long, but only nine metres deep and flanked by a busy inner-city street in the south. Due to these boundary conditions, all apartments have an extremely strong relation to the outside world.
In order to achieve a positive energy balance during operation, buildings and users must work together optimally. Each tenant has a specific energy budget, which is included in the rental price. Only when the residents consume more do they have to pay extra. On touch panels in each apartment, residents can read their energy consumption in real time and compare it to the available budget, the energy production of the photovoltaic system and an anonymous energy efficiency ranking of all apartments. On request, the system can also provide them with situational energy saving tips. The residents can also control the heating, ventilation system and sun protection via the touch panel.

Results
For two years, technical monitoring and several user surveys with questionnaires were carried out in the Aktiv-Stadthaus. It turned out that some of the residents preferred much higher room temperatures in winter than expected. The demand for hot water in the summer, on the other hand, was significantly lower than forecast. All in all, the Aktiv-Stadthaus achieved the targeted plus energy standard after its first year of operation by a slim margin.
In the survey, more than 60% of all respondents said that their homes were warm enough in the autumn, even without heating. Only a good one-fifth complained that the apartments quickly heated up in summer. However, the majority of residents described underfloor heating as sluggish and wanted a higher surface temperature. Satisfaction with mechanical ventilation decreased over time: after the first summer, only 43% of respondents said that the system always ensured good air quality. Most residents therefore also rely on window ventilation.
The overwhelming majority of residents in the Aktiv-Stadthaus find it important to know their own energy consumption – with a slightly decreasing tendency, which indicates a certain habituation effect. While, initially, more than half of the residents used the interface at least once a day, most of them have now settled on a weekly use. The most interesting question for them is how their own electricity and heat consumption compares to the energy budget and how they score on the internal energy efficiency ranking list.

History teaches us that buildings have to be robust. Robust refers to the materiality of the building and its simplicity but also to the architectural qualities of the building; arrangement and dimensionof the rooms, daylight — the ability to provide comfort and well-being. This type of robustness guarantees a long life for the building instead of assigning the users a kind of compulsory happiness.”

Design approach
The architect's office Baumschlager Eberle has designed a house with no heating, cooling or mechanical ventilation system as their new headquarters. The six-storey, white plastered cube stands in a suburban industrial area and houses an art gallery, a restaurant, a dwelling unit and several office floors. Its square floor plans are divided by inner walls, staircase and elevator cores in such a way that each room receives daylight and fresh air from two sides. The clear room height of 3.36 metres in the offices also contributes to good ventilation. Automatically controlled ventilation flaps next to the windows ensure fresh air supply and summer cooling. The only heat source is the people present and their electrical appliances, such as computers, photocopiers and coffee machines. If necessary, users can open
the ventilation flaps manually at any time. After a few minutes, they close automatically so that the space does not heat up or cool down unnecessarily. In this way, indoor temperatures of between 22 and 26°C are expected to prevail in the building all year round; hence the name of the project − 2226.

Results
Sensors distributed throughout the house measure energy consumption, indoor temperature, humidity and CO2 content of the indoor air every 10 minutes. In addition, experts determined the microbiological quality of indoor air during the first year of operation. The result: all measured values were within the optimum comfort range (IDA 1 = high indoor air quality) in accordance with EN 13779, and the temperatures in the house were always between 22° and 26°C in the first year − even during an intensive, three-week period of high temperatures shortly after moving in. The CO2 content of the air only rose to a maximum of 1,200 ppm as the ventilation flaps open automatically beyond this limit value. Compared to conventional office buildings with ventilation systems, the number of germs in the room air in house 2226 was two to three times lower than in conventional office buildings. In theory, this would mean that the indoor air quality in 2226 would even meet the demanding requirements for food processing.

How do you encourage your employees to move during a long office day? In ASID’s new head office, common areas are centralised so that people have to walk only a few steps to get there. Furthermore, the café and copy room also happen to be the only two areas with trash bins so that the employees have to walk there in order to dispose of their waste.

Design approach
Located in central Washington D.C., the new headquarters of the American Society of Interior Designers (ASID) occupies the northwest corner of a multi-tenant floor in a pre-existing office building. The 700 m2 office space has been conceived as a ‘free address’ environment without assigned seating. Employees can select from a variety of workspaces, depending on what best supports their specific tasks that day.
All workspaces have access to daylight and views outdoors. This is complemented by a circadian lighting system that mimics the daily colour cycle of natural daylight and provides a minimum of 250 melanopic lux for all work spaces with the help of colour-changing lamps. Daylight responsive controls ensure that the electric light is dimmed down depending on the daylight levels outside. Solar sensors mounted on the facade automatically track the position and intensity of the sun to adjust the automated shades accordingly.
As the facade has no operable windows, the design team took great care to ensure a good indoor air quality. All highly occupied office spaces were equipped with demand-controlled ventilation that keeps CO2 levels below 800 ppm all of the time. Carbon filters in the air, handling units of the building, provide enhanced filtration of VOCs and large particulates. The majority of the materials and furniture used in the office have either Health Product Declarations, DECLARE, or Cradle to Cradle certification.

Evaluation concept
The ASID headquarters is the first space in the world to receive Platinum-level certification both in the LEED and WELL standards. Both before and after moving in, the client undertook four interdisciplinary research projects to evaluate how the new spaces would affect the employees’ health and performance, their mutual interaction and a number of other factors.

Results
The indoor climate, employees’ satisfaction and work performance were all monitored in the new office space and then compared to the values achieved in ASID’s previous, interim office in a co-working space. This comparison yielded a 50% reduction in loudness, a 63% increase in brightness and a 60% reduction in indoor CO2 levels. In a post-occupancy evaluation, employees said that they were significantly happier with 14 out of 15 parameters (including air quality, thermal comfort, and light) than in the previous spaces. It was also found that people in the new office now work, on average, 19% longer hours than before. This may be due partly to their greater motivation but also to less sickness-related absence. Self-reported productivity has increased by 16% in the new offices.

The specification of healthy, local and recycled materials played a major role in the design of the Omega Center. This also involved unconventional solutions; for example, the project team had to make their own pipe insulation because they could not find any free of toxins. Re-used materials employed in the construction include doors from an office building, bathroom partitions salvaged from a church, and even plywood from former President Barack Obama’s inaugural stage.

Design approach
The Omega Center for Sustainable Living combines an environmental education facility and natural water reclamation plant on the client’s 80-hectare campus in upstate New York. Wastewater from the campus is cleaned here by the earth, plants and sunlight in a 600-m2 greenhouse, and courses on environmental subjects are taught in an indoor and outdoor classroom. In order to create an indoor environment that is both comfortable for people and fertile for the plants, the building incorporates both passive (daylight, passive solar heating, natural ventilation) and mechanical (geothermal, fans, electric lighting) systems.
With the main facades pointing north and south, the building’s orientation allows optimal control of daylight and solar heat gain. Solar tracking skylights were installed in the greenhouse to accurately optimise daylight levels.
Manually operable windows are provided in each occupied space, and the plants in the wastewater treatment system remove CO2 from the air while producing oxygen. High-level clerestory windows ventilate the lobby, mechanical room and restrooms using the stack effect. Fresh air enters through windows in the south facade, channelling prevailing breezes that have been cooled whilst moving over the wetlands into the building. Four of the rooms have been equipped with sensors that trigger an alarm if CO2 levels rise above 800 ppm, thus reminding the users to open a window.

Evaluation concept
The Omega Center for Sustainable Living was the first building to achieve both LEED Platinum and Living Building Challenge certification.

Results
During the first year of operation, the Omega Center fulfilled all relevant criteria for Living Building Challenge certification. Net Positive Water was achieved thanks to the in-house water treatment facility and on-site wells, so that water is both taken from and returned clean to the water table. Also, rainwater is collected in a cistern and re-used for toilet flushing and irrigation of the grounds.
With its photovoltaic solar panels on the roof and geothermal heat pump system, the Omega Center achieved an energy surplus of 9,000 kWh in the first year of operation. As part of the Living Building Challenge certification, a user survey was conducted on whether the design features in the building contributed to “human delight and the celebration of culture, spirit and place appropriate to the function of the building”. The results were almost unanimously positive. Praise was given particularly to the light and spaciousness of the interior spaces, the beautiful views outside, the sense of closeness to nature evoked by the plants inside and the used timber cladding of the building’s facades.

“I find the combination of light, water and flourishing plants makes for a truly uplifting space, especially when you know its purpose. It's one of my favorite places on campus”

Response from the user survey

One of the residents, Gioya Bouwman, reports that she now pays 65 € per month for energy in her new house, whereas she paid 230 € in her previous home. In the meantime, Gioya Bouwman has also closed off the previously open staircase with an additional door. She admits that the daylight from the roof windows flooding downstairs through the stairwell had been nice but the downside of the open space was that kitchen odours and noise also spread throughout the entire house.

Design approach
In Montfoort, near Utrecht, the first ten row houses in the Netherlands have been refurbished to Active House Standard, and now achieve an A+ label for energy performance. New rooftop extensions add 17 m2 of living space to the previously unused attic floor of each house. The new roofs are equipped with roof windows on both sides as well as 19.5 m2 of PV panels and 4.5 m² of solar collectors per house. The size of the facade windows remained unchanged but the new roof windows, together with the open staircase, result in average daylight factors between 3.6% and 11% in the various rooms. All the facades were fitted with new insulation, new brick facing and new weatherboarding carefully selected to make the houses blend in with the rest of the residential district.
To ensure optimum air quality, the houses rely on a hybrid ventilation system. For most of the year, they can be cross-ventilated via the facade windows, and the automatically operated roof windows, together with the open staircase, create a chimney effect in the centre of the house that ‘sucks’ stale air out of the building. In winter, a mechanical ventilation system with heat recovery (controlled by CO2 sensors) comes into operation. Heating is supplied by electrical ground source heat pumps, allowing the previous gas heating system to be discarded entirely.

Evaluation concept
The electricity consumption of the various houses and the electricity production from the solar panels were measured for two years, and questionnaires handed out among the tenants every half year in order to be able to better interpret the monitoring results. Alongside this, touchscreens are installed in every home so that the residents can keep an eye on their energy consumption themselves.

Results
>The energy monitoring comprised both the Active Houses and seven similar houses in the neighbourhood that had undergone a standard refurbishment to energy class A at the same time. This made a comparison of the different refurbishment approaches possible.
Over the two-year period, the Active Houses consumed 68% less energy than an average, unrefurbished Dutch row house of the same size, and 40% less than the refurbished ‘Class A’ houses in the neighbourhood. Half the energy consumption in the Active Houses was met by solar energy from their own roofs.

The design concept for the houses was developed in a competition organised by the German Federal Ministry of Construction, Transport and Urban Development (BMVBS) in 2012. In total, two adjacent rows of three apartment buildings were each renovated according to the Efficiency House Plus standard.

Design approach
Just a few years ago, the three apartment buildings from 1938 were dilapidated and hardly inhabitable. Today, they are the first existing buildings of their kind in Germany to be renovated to the Effizienzhaus Plus (Efficiency House Plus) standard as part of a pilot project. Over the course of the year, they are expected to generate more energy on site than their residents consume.
Almost the entire southern surface of the roof is now seamlessly covered with photovoltaic modules. The only exception is eight roof windows, which have been fitted flush with the solar system. The outer walls and the roof received new insulation, the cellars were drained and a new heat pump heating system installed. Other decentralised heat pumps use the heat from the exhaust air to generate hot water. Fresh air enters the rooms through valves that are integrated behind the radiators in the outside walls. In addition, residents can manually operate the windows to let in fresh air (hybrid ventilation system).
Inside the houses, the apartments have become larger and brighter, not least due to the addition of two new, two-storey annexes on the north side of the building. The windows are now floor level and allow much more daylight into the apartments than before. The attics, which were previously used for storage and laundry drying, have been transformed into fully-fledged living spaces. They were combined with the apartments on the upper floor to form generous maisonettes. The architects had the false ceiling removed above the dining areas, so that a two-storey air space connects both levels and daylight falls through the roof windows down to the dining table.

Results
During the first year of operation, energy consumption in the houses was higher than anticipated. This was mainly due to deficiencies in the construction, incorrect settings and the optimisation process, which had not then been completed. The problems were solved after the first year of operation. The optimisation process will continue, particularly in the area of heat pump settings.
For these reasons, the targeted positive energy balance was not quite achieved after the first year of operation. However, the engineers expect that future measures to optimise operations will lead to a positive annual balance.
Parallel to the technical measurements, the Berlin Institute for Social Research also conducted tenant surveys. However, due to the small number of people surveyed and the complications with the building services mentioned above, no representative results have yet been obtained. The residents responded positively to the questions about the quality of living, the layout of the apartments and the connection to the outside.

Extensive carbon profiling studies were undertaken in the planning phase to minimise embodied carbon in the building construction. These also resulted in some unconventional measures, such as the choice of double rather than triple glazing in the main west and east facades.

Design approach
The new headquarters of WWF-UK houses 340 employees on two storeys in an open-plan environment, together with conference and educational facilities, as well as an exhibition space. The building, which is rated BREEAM Outstanding, was erected over an existing car park on the banks of the Basingstoke Canal. Great care was taken to ensure natural ventilation and good daylighting across the deep plan, with an average daylight factor of 3.1% on the ground floor and 5.1% at the mezzanine level. The Living Planet Centre can run for about two-thirds of the year on natural ventilation. This is supported by four characteristic cowls on the roof that use buoyancy and local winds to ‘suck’ stale air out of the building. Green and red lights distributed across the work areas show whether the building is in natural or mechanical ventilation mode.

Results
Together with the contractor Willmott Dixon, WWF’s building management team conducted a monitoring and user enquiries with questionnaires during the first year of operation. The contractor also undertook smoke tests to verify the ventilation rates in the meeting rooms.
Although the building performed considerably better than the industry benchmarks, the first year’s energy consumption was roughly 50% higher than anticipated. This may be due partly to the fact that the public areas of the building, as well as the conference and educational facilities, have proved very popular and, as a result, the operating hours are longer than anticipated.
Adjustments were made to the ventilation system in particular, in cluding the night-purge routine that ‘flushes’ the building with cool air during summer nights to maintain comfortable temperatures. Extra vents were added to the meeting rooms to increase the extraction rates. The four roof cowls, the operation of which had originally been intended to depend only on wind and buoyancy, were equipped with additional manual controls.

Designing and building the NeighborHub was a huge collaborative effort. More than 250 students from a broad spectrum of disciplines and 150 supervisors from various sectors were involved in the project, devoting over 7,500 working hours. The entire project had a budget of roughly $4.2 million and ran over three years.

Design approach
This experimental plus-energy building was the overall winner at the 2017 U.S. Solar Decathlon in Denver. Beyond being useable as a private home, the NeighborHub was conceived as a ‘house for neighbourhood living’. The student team chose seven themes, such as energy, waste management, biodiversity, mobility and food, that guided the entire project.
From May 2018 onwards, the building will find a permanent location in Fribourg, Switzerland, on a former brewery site that is now used as an innovation district and research centre. Here the NeighborHub will serve as a place for discussion as well as a demonstrator of future technologies.
The climate concept of the house differentiates between a thermally controlled core and an ‘extended skin’ along the perimeter, which is neither actively heated nor cooled and where indoor temperatures thus fluctuate. The latter is shielded against the outside world by translucent polycarbonate and transparent acrylic panels for passive solar gain and natural light, as well as opaque facade modules for active solar technology, both thermal and photovoltaic. The majority of the facade can be folded upwards so that the NeighborHub opens out entirely to its environment. Even when it is closed, the transparent panels provide views outside, and four fully glazed sliding doors also allow daylight to penetrate into the building’s core.
Three modular skylights with semi-automated shading – two for the core and one row of modules for the perimeter area – provide the indoor spaces with additional daylight and support the natural ventilation. The electric light is dimmable and equipped with variable colour control in order to help the users maintain a natural sleep/wake cycle.

Evaluation concept
All entries to the Solar Decathlon are evaluated in ten categories, six of which rely on qualitative and four on quantitative criteria. To earn full points on the ‘Health and Comfort’ category, teams must maintain temperatures between 20°C and 23.3°C, relative humidity between 35% and 60%, indoor CO2 levels below 1,000 ppm, and provide the building with an airtight envelope.
The NeighborHub is equipped with wireless sensors that keep track of the indoor climate. A weather station also monitors the outdoor climate and provides forecasts of solar irradiation, wind and rain.
Once the building is operational in Fribourg, the monitoring will resume, with the results being used to refine the control algorithms for the ventilation, heating, cooling and solar shading.

Results
Alongside the overall Solar Decathlon competition, the NeighborHub also won first prize in six of the ten categories. Of particular interest were the full (100/100) points in both the engineering and the architecture contest. Another first place was achieved in the Health and Comfort category, with 97.165 out of 100 points. Temperatures and CO2 levels only rose above the maximum permissible limits in a few rare instances. Results were somewhat more mixed in terms of humidity, with values below 20% reached on two of the eight days of the evaluation. Although the control systems in the house prioritise passive strategies over active heating and cooling, the tight constraints of the competition rules in terms of indoor temperatures meant that a cooling unit had to be installed in the house. When the building enters into permanent operation in Fribourg, the thermal requirements will be less strict. The student team thus hopes that there will be less need for active cooling and the passive design of the perimeter area can be used to a greater degree to ensure a stable indoor climate.

Atika was initially conceived as a rooftop extension to be used for residential purposes. The fact that the building now stands on the ground, and is used as an office and laboratory space, proves the versatility of the initial design.

Design approach
Under the name of Atika, this building was originally conceived by the VELUX Group as a model home for the Mediterranean Climate. The company eventually decided to donate it to Politecnico di Milano, as a laboratory for experimentation with new materials and energy technologies. VELUXLab is the first nearly zero energy building on an Italian university campus.
The light-weight steel structure and overall layout of the building were preserved in the refurbishment but the build-up of the walls and roof were modified to better match the climate of Milan. VELUXLab is built around a south-facing patio that is accessible from all the rooms. The pitched roofs are designed to maximise shade in summer and solar gains in winter and to enhance natural ventilation. In spring and autumn, the roof windows are operated to ventilate used air out of the building. In summer and winter, VELUXLab relies on mechanical ventilation with heat recovery and a reversible air-to-water heat pump to maintain comfortable temperatures. Three solar panels on the roof supply all the hot water needed in the building. Furthermore, 2 kWp of PV panels have been installed on the roof.
The electric lighting in VELUXLab is equipped with sensors and dimmers to that it can be automatically regulated, depending on available daylight levels. The indoor ceilings are finished with perforated acoustic panels made of plasterboard with added zeolite that are capable of cleaning the indoor air of pollutants.

Evaluation concept
In a first step, 14 temperature sensors were placed inside the walls and roof, and on their surfaces, to monitor the thermal behaviour of the construction. A further six temperature sensors and two electricity meters monitor the energy flows in the mechanical system. All of these are connected to a wire less node network, with the results broadcast in real time on the University intranet. In a second step, the VELUX Lab is now being equipped with Leapcraft sensors (see also the article on Green Solution House) that allow for a continuous monitoring of CO2, humidity, particulate matter, VOCs and daylight levels.

Results
In 2011, the building was left empty, and monitored to validate the design strategies after completion of the refurbishment. Since 2012, the researchers’ team of Politecnico di Milano has occupied the spaces; several people work there every day, thus influencing the thermal behaviour and indoor comfort of the building.
The temperature sensors have delivered huge amounts of data about the thermal behaviour of the building and the thermal comfort inside it. Once the Leapcraft sensors are installed, the research team hopes to get an even more comprehensive overview of the indoor comfort. The daylight-dependent lighting controls have helped to reduce electricity demand for lighting by almost 80% compared to a standard solution. The sensors deployed in the mechanical system show that up to 35% of the monthly electricity consumption in VELUXLab is met by the rooftop PV panels in summer.

In the NO-tech house, the architects decided to promote outdoor living. The house has both an outdoor kitchen and outdoor shower for use during summer, to prevent moisture and particles from accumulating in the house.

Design approach
These three single-family homes, called YES-tech, NO-tech and NOW-tech, explore the effects of different design strategies on indoor comfort and indoor air quality.
The NOW-tech house was built according to current practice with standard materials and technical solutions. The YES-tech house has a zone-divided, demand-driven ventilation system equipped with CO2, particle, moisture and temperature sensors in each room. Fresh air enters the rooms through thousands of little perforations in the ceiling in order to avoid drafts. A powerful extraction hood in the kitchen directly extracts particles at the source. In the NO-tech house, priority is given to low-emission and moisture absorbing materials to maintain a good air quality. The kitchen is divided from the rest of the house by a glass partition wall. The children have both a bedroom and a separate playroom at their disposal to protect them from any emissions from their toys while they sleep. Instead of a centralised MVHR system, four solar chimneys equipped with roof windows and heavy, clay-brick walls have been placed in different rooms to improve natural ventilation. Small exhaust fans have been placed inside the solar chimneys to get rid of the used air even during cloudy skies.

Evaluation concept
The Indeklimahjulet (Indoor Climate Wheel) tool was specifically developed for the design of the Sunde Boliger in order to achieve a balance between health and comfort in the indoor climate. A total of 12 aspects are considered, half of which are accessible to our senses (such as daylight, humidity or temperature) while the other half usually escape our perception but significantly impact human health (such as particulate matter and the off-gassing of furniture and building materials). Upon completion of the buildings, the engineers performed numerous air quality measurements to establish a baseline with which the air quality during occupancy can later be compared. Once the homes are occupied, the monitoring will continue for another two years. This includes the air exchange rates and air velocities in the various spaces, the relative humidity at different ventilation rates, CO2 levels, the indoor temperatures in all rooms, and the distribution of particles in the indoor air. Furthermore, the monitoring will keep track of VOC and other emissions from furniture and building materials. Alongside the physical measurements, the residents will be interviewed several times, asking them about factors such as the smells they perceive, the indoor temperatures and the noise levels.

Results
As the residents will not move into their homes until spring 2018, no monitoring results from the occupancy phase are available. However, a first test of the actual air exchange rates after building completion showed similar results both for the NO-tech house (in the case of natural ventilation only) and the YES-tech houses. Both were higher than the values measured in the NOW-tech house, and significantly above the minimum air exchange stipulated by the Danish Building Regulation.
A second test also proved the effectivity of the powerful ventilation hood in the YES-tech house when it came to reducing particulate matter in the kitchen. Compared to the NOW-tech house (which has a less effective kitchen hood installed), the particulate matter concentration rose to much lower peak levels during cooking.